Improvement in key-hole guards for locks



r 2Sl1eets--Sheef 1 y J. M. ALDEN. Improvement in Key-Hole Guards forLocks.

N0.'124,874, PatentedIVlarch26,i872

N B a \WxYna-n 2:

AM. PHOTO-LITHOGRAFHIL m. M Y losaamvr': mammal '2 Sheen-"Shem 2' V J.M. ALDEN. Emprovement in Key-Hole Guards for Locks.

Patented March 26,1872

iznsre JAMES M. ALDEN, OF NEIV ROCHELLE, NEW YORK.

IMPRQVEMENT IN KEY-HOLE GUARDS FOR LOCKS.

Specification formihg part of Letters Patent No. 124,874, dated l\l11l'011 26, 1872.

To all whom it may concern:

,Be it known that I, JAMEs M. ALDEN, of New Rochelle, in the county ofWestchester, in the State of New York, have invented certain new anduseful Improvements in Door- 1I ocks, of which the following is aspecifica- The invention relates to improvements upon the lock describedin the patent of John R. Marston, dated June 15, 1858, in which there isa plate which covers the outside key-hole whenever the door is lockedfrom the inside of theapartment or building. The improvements enable thelock to hold the door by both bolts -to wit, the main-lock bolt and thelatch-bolt. They also cause the key-hole'cover plate to further increasethe security of the look by abutting against the main bolt, and aidingto resist any force tending to throw it back or withdraw it. I alsoprovide for guarding the hole which admits the latch-key tooperatethenightlatch in front doors; and also for holding the parts ofthe lockbetter-in position when the lock is taken apart to inspect orrepair any portion.

The following is a descriptionof what I consider the best means ofcarrying out the in vention.

The accompanying this specification.

Figure 1 is a view of the main body of the lock with the cap or backplate and its attachments removed. Fig. 2 is a face view of the drawingforms a part of back plate and its attachments. Both these fi g uresshow the lock in the unlocked condition. Fig. 3 is a view of the entirelock, with certain portions of the back plate broken away to show theinterior. This shows the lock in the locked condition, as locked fromthe inside of the building or apartment. Fig. 4 is a planview or rathera horizontal section on the line S S in Fig. 3.

Similar letters of reference indicate corre sponding parts in all thefigures.

The scale is full size. 7 i

A is the main casing, and A the cap or back plate fitted thereto andserving therewith in the usual manner. 13 is the main bolt, and O is thelatch-bolt. The several portions of these, which are important to bereferred to, are marked A B O.

The latch-bolt O isoperated by the knob and a spring in the ordinarymanner. The peculia ri ties in the construction and operation of thelatch-bolt lie in these two points-that it is provided with aprojection, G, reaching downward toward the main bolt B; and that it isso proportioned as to bear against the central boss A when in itsextreme outward position,

so that it will remain in that position without allowing the parts to bedisturbed by the ac-. tion of the spring when the back plate A and itsattachments are removed from the lock.

D is the ordinary tumbler, which holds the main boltB by the ordinarymeans in itslocked or unlocked position. E is the coverin g-plate, whichperforms all the functions of the corresponding part in the Marstonpatent referred to, and is held in place, in the locked or unlockedposition, by the tumbler G. I have adapted the covering-plate E tofulfil two additional functions by providing it with the arm E, whichprojects upward and engages with the arm 0 on the latch-bolt, and byelongating and adapting the end, by a flange, E to abut against ashoulder, B, on the main bolt B, which shoulder is made square toreceive it, thereby aiding to maintain, againstany violence, the lockedposition of the bolt.

It may be proper to explain briefly that the coveringplate E in theMarston lock and in this look moves forward with the main bolt 13 andcovers the outside key-hole whenever the lock is operated from theinside of the apartment; but, whenever the lock is operated from theoutside of the apartment, the cover ing-plate E and its adjuncts remaininoperative. The peculiar effects of my lock are all available only whenthe lock is locked from the inside of the building or room.

The construction of the coveringplate to perform the additional dutiesrequired in my invention involves no peculiar difficulties. I prefer tomake the covering-plate somewhat thicker and stronger than has beenheretofore usual in the Marston lock, so that its arm E engaging withthe arm 0 of the latch-bolt, shall hold the latchbolt 0 very strongly inthe locked position, giving the door all the security due both to themain bolt B and the latch bolt 0. I elongate and thicken the end E ofthe covering-plate E where it abuts against the shoulder B of the mainbolt B, so that it has a broad and firm bearing. It may be proper toremark that the post a, usually a boss formed upon the inner face of theback plate A to carry the tumbler G which holds the covering-plate,'should be made strong, and the parts should be well fitted thereto.

The function of the arm 0, by bearing with its front edge against theboss A in the center of the frame-work, will be very readily understood,and the proper conformation and adaptation of the parts will involvelittle difficulty. Room must be left to allow the spring to throw thelatch-bolt out to its full extent and no more. Immediately on reachingits full throw the front of the arm 0 should bear against the boss AThis is most easily accomplished by making the arm 0 a little too wideand milling or filing away a little on each lock to bring it just right.

In those locks which are provided with nightlatohes I make the arm E ofthe coveringplate E of such width that it will cover the hole for thenight-key at the same time that it covers and guards the hole for themain key. The position of the night-latch key-hole, to serve with onlythe width of the arm E here shown, is indicated in dotted lines in Fig.2, and marked H.

It will be understood that the flange E on the covering-plate E may beeither cast thereon, or soldered, or fastened by rivets, or otherwisesecured. Its function is to set up against the shoulder B 011 the boltB, securely holdin g it in its place, and necessitating the foreing backof the covering-plate or slide E before the bolt of the lock can bepushed or thrown back. The flange may be the whole width of the bolt oronly a portion of the width.

The improvements do not detract at all from the full performance of allthe functions of the Marston lock. They add but very little to theexpense of the construction. There is not a single new part required.But they impart very important new qualities to the look.

It will be observed that my look only engages the bolts together whenlocked from the inside, and leaves bolt-catch unaffected when lockedfrom the outside. This makes it easy for a servant or other person toascertam by trying the knob whether the door has been locked from theoutside or inside, and thus to determine whether the occupant is withinand should not be disturbed, or has gone out leavin g the room free tobe entered by the master key and set to rights.

The pivot of the tumbler G, which guards the covering-plate E, being onthe cap A en tirely independent of the ordinary lockin g parts, enablesit, by the abutting of the plate E against the shoulder B, to contributeits strength most effectually to the security of the main bolt againstviolence.

I claim as my invention- 1. The arm E on the covering-plate E, ar rangedto engage with the arm 0 on the latchbolt 0 when locked from the insideof the room, as herein specified.

2. I claim the combination and arrangement of the parts E E, B B, O C,and G, whereby the covering-plate E E is caused to cover both theordinary key-hole and the latch-key hole 11, and also to engage with thelatch-bolt G G and aid in sustaining the main bolt 13 B, as hereinspecified.

In testimony whereof I have hereunto set my name in the presence of twosubscribing witnesses.

JAMES M. ALDEN.

Witnesses:

THOMAS D. Srnrson, (J. O. Lrvnves.

